Drinking cups for infants and children are old and well-known. Such cups are sometimes referred to as "training cups" and are intended to be the next step beyond the use of a baby bottle to teach children to drink from a glass or cup.
Such drinking cups typically include a container, or "tumbler" portion which holds the liquid and a cover which attaches to the tumbler and which covers all or most of the opening of the tumbler. Use of the cover is intended to minimize spills which may otherwise occur when the child drops or upsets the cup and allow the child to tip the cup upward to a drinking position without having the entire contents of the cup pour out all at once. Examples of such cups are shown in already-issued U.S. patents.
For example, U.S. Pat. No. 2,640,337 (Bryant) shows a baby cup having a lid which covers a substantial portion of the tumbler opening and has a hole through which the child may drink. U.S. Pat. No. 2,765,632 (Bryant) shows generally the same type of cup with a cover that entirely closes off the tumbler opening with the exception of a passage through which the child may drink.
U.S. Pat. No. Des. 216,730 (Carslaw) and U.S. Pat. No. D. 233,972 (Juhlin) both show drinking cups having lids which completely close off the tumbler opening, with each lid having a spout through which the child can drink. Both of these references also show the use of handles attached to the outer periphery of the cup to provide a convenient hand grip for the child. A similar construction is shown in U.S. Pat. No. 2,792,696 (Stayart) showing a cup with handles and with a cover that completely closes off the tumbler opening.
U.S. Pat. No. 3,412,892 (Waksman, et al.) shows a cup with a lid having a drinking opening that may be selectively opened or closed. U.S. Pat. No. 4,850,496 (Rudell et al.) shows a drinking cup having a tumbler with external screw threads formed at its uppermost periphery and a series of interchangeable lids which may be attached to the top of the cup, with the lids varying from a nipple-like arrangement to a collar which approximates an open-mouthed cup. U.S. Pat. No. 4,600,111 (Brown) shows another cup construction which uses a threaded collar to hold different cup covers in place, allowing the cup to be used in configurations ranging from a baby bottle to a training cup.
U.S. Pat. No. 4,121,731 (Okerstrum) shows a child's drinking cup having a pair of handles which must be squeezed inwardly in order to open the lid closure to allow a child to drink from the cup.
One common characteristic of such cups is that the efficacy of the cup will be completely destroyed should the child learn how to remove the lid, allowing the liquid inside to spill either when the cup is upset or during the child's attempts to drink from the cup without fully having learned to do so. If the lid is too easy to remove, the cup's usefulness as a training device is extremely limited. If the lid is too difficult to remove, this will discourage the use of the cup by adults who will find it inconvenient or awkward to open the cup to put liquid in it, or to wash the cup.
The concept of producing a container with a lid more easily removable by an adult than a child is also well represented in the prior art by patents drawn to child-resistant closures for securing containers which contain drugs, medicines or such potentially hazardous or poisonous substances as cleaning fluids.
Typical and representative of such devices is U.S. Pat. No. 4,429,800 (Greenspan) which shows a container and lid combination. The lid may be removed only upon the simultaneous depression of a pair of tabs on the lid and these tabs are sized and spaced to make it much easier for an adult to manipulate them than a child. U.S. Pat. No. 4,087,016 (Towns et al.) shows a safety cap which must be rotated with respect to the container to a predetermined position before the cap can be disengaged from the container.
U.S. Pat. No. 4,807,768 (Gach) shows a snap-cap which, when closed, requires the simultaneous compression of a pair of oppositely-disposed tabs to enable the cap to be opened. U.S. Pat. No. 4,830,206 (Fisher) describes a tamper-resistant container having a lid with a pair of internally-extending ears which interconnect with a pair of hooks formed on the interior of the container. In order to release the hooks, a specific portion of the lid's periphery must be compressed while the container is simultaneously twisted or rotated with respect to the lid. U.S. Pat. No. 4,442,945 (Sandhaus) shows a safety closure having both a locking and non-locking mode so that the user may select which mode is appropriate.
U.S. Pat. No. 4,345,691 (Burke) shows a closure for spray containers or other types of dispensing bottles with an anti-opening mechanism which is not designed to be defeated, thus making it possible to assemble a spray bottle with a spray top which cannot be removed.
Another feature which is described in the prior art with respect to safety closures is the type of closure that has a series of inter-connecting latches, typically engaged when the lid of the container is rotated with respect to the container. Several such constructions use a biasing element to urge the lid upward, that is, away from the container to enhance the positive latching feature. Thus, the biasing of the lid or cover forces the mating portions of the latch more tightly together.
U.S. Pat. Nos. 4,526,281 (Herr) and 4,053,078 (Herr) teach and describe a closure having lugs formed on the interior of the cover which interengage with hooks or latches formed on the outer periphery of the container. Biasing of the lid with respect to the container is accomplished by either a fitment spring or by pressure exerted by the uppermost portion of the container against the lid.
U.S. Pat. Nos. 4,059,189 (Mumford) and 4,383,619 (Mumford et al.) illustrate a closure having a similar arrangement, with the interior periphery of the lid having a number of lugs formed thereon which mate with projections formed on the outer upper periphery of the container. A separate liner is placed across the container opening to act as a biasing element forcing the lid upward with respect to the container when the lugs are engaged with the projections.
U.S. Pat. Nos. 4,627,547 (Cooke '547) and 4,739,890 (Cooke '890) show containers having lids with hook elements positioned around the inner periphery with mating latch elements positioned around the outer upper periphery of the container. A resilient pad or liner is inserted into the lid which is then compressed against the container when the lid is forced down and twisted in order to engage the mating hook members.
A medicine vial bearing the notation "U.S. Pat. No. 4,739,890" has been inspected and is shown herein as part of the drawings. The vial has a lid with lug members formed about the inner periphery, and a container with mating latches formed about its outer upper periphery. Similar features are shown in the '890 and '547 Cooke patents.
The lid also has an inner cylindrical skirt attached to the underside of the cap which forms an annular channel between the skirt and the sidewall of the cap. Holes are formed through the top of the cap which extend into the annular channel. The upper, inner portion of the container is thickened slightly inwardly, top to bottom. None of these features are described in either the '890 or '547 Cooke patents, nor are they explained in U.S. Pat. Nos. 3,888,376, 3,952,899, 4,139,112, 4,434,903 or 4,706,837, all issued to Cooke as well.
U.S. Pat. No. 4,834,251 (Yu) shows a medicine bottle having a measuring cup which attaches over the cover for the bottle. The base of the cup is formed with a convex section which, when placed over the opening to the bottle, is compressed. A series of projections is formed on the outer periphery of the bottle which mate with corresponding latch elements formed on the interior of the measuring cup. The biasing force exerted when the concave bottom of the measuring cup contacts the bottle cover serve to hold the latching mechanisms in closer engagement.